(20) باب قَتْلِ الْوَلَدِ خَشْيَةَ أَنْ يَأْكُلَ مَعَهُ
Narrated `Abdullah:
I said 'O Allah's Messenger (ﷺ)! Which sin is the greatest?" He said, "To set up a rival unto Allah, though He Alone created you." I said, "What next?" He said, "To kill your son lest he should share your food with you." I further asked, "What next?" He said, "To commit illegal sexual intercourse with the wife of your neighbor." And then Allah revealed as proof of the statement of the Prophet: 'Those who invoke not with Allah any other god)................. (to end of verse)...' (25.68)
Reference: Sahih al-Bukhari 6001
In-book reference: Book 78, Hadith 32
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 8, Book 73, Hadith 30